Alginate Research Articles

A High-Stretching, Rapid-Self-Healing, and Printable Composite Hydrogel Based on Poly(Vinyl Alcohol), Nanocellulose, and Sodium Alginate.

Hydrogels with excellent flexibility, conductivity, and controllable mechanical properties are the current research hotspots in the field of biomaterial sensors. However, it is difficult for hydrogel sensors to regain their original function after being damaged, which limits their practical applications. Herein, a composite hydrogel (named SPBC) of poly(vinyl alcohol) (PVA)/sodium alginate (SA)/cellulose nanofibers (CNFs)/sodium borate tetrahydrate was synthesized, which has good self-healing, electrical conductivity, and excellent mechanical properties. The SPBC0.3 hydrogel demonstrates rapid self-healing (<30 s) and achieves mechanical properties of 33.92 kPa. Additionally, it exhibits high tensile strain performance (4000%). The abundant internal ions and functional groups of SPBC hydrogels provide support for the good electrical conductivity (0.62 S/cm) and electrical response properties. In addition, the SPBC hydrogel can be attached to surfaces such as fingers and wrists to monitor human movements in real time, and its good rheological property supports three-dimensional (3D) printing molding methods. In summary, this study successfully prepared a self-healing, conductive, printable, and mechanically superior SPBC hydrogel. Its suitability for 3D-printing personalized fabrication and outstanding sensor properties makes it a useful reference for hydrogels in wearable devices and human motion monitoring.

Enhanced treatment of acute organophosphorus pesticide poisoning using activated charcoal-embedded sodium alginate-polyvinyl alcohol hydrogel.

The adsorption of activated charcoal is currently a major clinical treatment for acute organophosphorus pesticide poisoning (AOPP). However, the adsorption duration and efficiency of this method is unstable. In this study, a hydrogel embedding activated charcoal was prepared and its alleviating effects on AOPP were investigated. A composite hydrogel using sodium alginate and polyvinyl alcohol (SA-PVA) hydrogel was prepared in this study. The structural properties of the SA-PVA hydrogel were characterized via multiple analysis including FTIR, TGA, XRD, SEM, tensile strength and expansion rate. Based on these, activated charcoal (AC) was embedded within the SA-PVA hydrogel (SA-PVA-AC) and it was used for the treatment of AOPP. Structural characterization indicated SA-PVA hydrogel possesses excellent mechanical properties and biocompatibility. The invivo study demonstrated that SA-PVA-AC significantly alleviated the inflammation and oxidative damage in the liver, as evidenced by reduced levels of IL-6, TNF-α, and, IL-1β, SOD, and MDA. Furthermore, SA-PVA-AC treatment effectively re-regulated the activities of serum AST and ALT, exhibiting an improved effect on liver function. The findings suggest that activated charcoal embedded within SA-PVA hydrogel has significant potential as a therapeutic agent in treating AOPP, and offering a novel approach to managing pesticide-induced toxicity.

Study on Adsorption Properties of New Sodium Alginate and Chitosan Quaternary Ammonium Salt for Heavy Metal Ions

Study on Adsorption Properties of New Sodium Alginate and Chitosan Quaternary Ammonium Salt for Heavy Metal Ions

Antifungal Capacity of Microcapsules Containing Lactiplantibacillus plantarum TEP15 or Lactiplantibacillus pentosus TEJ4

The use of lactic acid bacteria (LAB) for the biocontrol of fungi that cause fruit and vegetable deterioration is a highly promising strategy. However, one of the main challenges lies in maintaining both viability and antifungal activity even in conditions that are unfavorable for LAB. The microencapsulation of LAB can minimize the impact of environmental conditions, helping to maintain viability, but there is still little information on what occurs with respect to antifungal activity. Therefore, the objective of this study was to evaluate the effect of microencapsulation with several polymer blends on the viability and antifungal activity of Lactiplantibacillus plantarum TEP15 and L. pentosus TEJ4. Sodium alginate (2%), sodium alginate–gum arabic (2%:1%), sodium alginate–k-carrageenan (2%:0.05%), and sodium alginate–whey protein (0.75%:1.5%) were used as encapsulating polymers. After processing (day 0), as well as after 14 and 28 days of storage, the encapsulation efficiency, moisture content, bead size, and survival were evaluated. Likewise, the encapsulated bacteria were subjected to in vitro tests against Colletotrichum gloeosporioides, Penicillium AT21H10, and Fusarium sp. Capsules with sizes ranging from 1.47 mm to 1.88 mm were obtained, and all the wall materials tested had more than 85% encapsulation efficiency and allowed survival rates greater than 90% and 80% to be maintained after 14 and 28 days of storage, respectively. The encapsulated LAB inhibited the growth of mycelia by up to 100%, but, against spores, the greatest inhibition was 22.08% for all the fungi tested.

Ion-Cross-Linked Hybrid Photochromic Hydrogels with Enhanced Mechanical Properties and Shape Memory Behaviour.

Shape-shifting polymers usually require not only reversible stimuli-responsive ability, but also strong mechanical properties. A novel shape-shifting photochromic hydrogel system was designed and fabricated by embedding hydrophobic spiropyran (SP) into double polymeric network (DN) through micellar copolymerisation. Here, sodium alginate (Alg) and poly acrylate-co-methyl acrylate-co-spiropyran (P(SA-co-MA-co-SPMA)) were employed as the first network and the second network, respectively, to realise high mechanical strength. After being soaked in the CaCl2 solution, the carboxyl groups in the system underwent metal complexation with Ca2+ to enhance the hydrogel. Moreover, after the hydrogel was exposed to UV-light, the closed isomer of spiropyran in the hydrogel network could be converted into an open zwitterionic isomer merocyanine (MC), which was considered to interact with Ca2+ ions. Interestingly, Ca2+ and UV-light responsive programmable shape of the copolymer hydrogel could recover to its original form via immersion in pure water. Given its excellent metal ion and UV light stimuli-responsive and mechanical properties, the hydrogel has potential applications in the field of soft actuators.

Flexible Multimodal Magnetoresistive Sensors Based on Alginate/Poly(vinyl alcohol) Foam with Stimulus Discriminability for Soft Electronics Using Machine Learning.

Flexible foam-based sensors have attracted substantial interest due to their high specific surface area, light weight, superior deformability, and ease of manufacture. However, it is still a challenge to integrate multimodal stimuli-responsiveness, high sensitivity, reliable stability, and good biocompatibility into a single foam sensor. To achieve this, a magnetoresistive foam sensor was fabricated by an in situ freezing-polymerization strategy based on the interpenetrating networks of sodium alginate, poly(vinyl alcohol) in conjunction with glycerol, and physical reinforcement of core-shell bidisperse magnetic particles. The assembled sensor exhibited preferable magnetic/strain-sensing capability (GF ≈ 0.41 T-1 for magnetic field, 4.305 for tension, -0.735 for bending, and -1.345 for pressing), quick response time, and reliable durability up to 6000 cycles under external stimuli. Importantly, a machine learning algorithm was developed to identify the encryption information, enabling high recognition accuracies of 99.22% and 99.34%. Moreover, they could be employed as health systems to detect human physiological motion and integrated as smart sensor arrays to perceive external pressure/magnetic field distributions. This work provides a simple and ecofriendly strategy to fabricate biocompatible foam-based multimodal sensors with potential applications in next-generation soft electronics.

Multifunctional Hydrogel of Recombinant Humanized Collagen Loaded with MSCs and MnO2 Accelerates Chronic Diabetic Wound Healing.

Chronic wound repair is a clinical treatment challenge. The development of multifunctional hydrogels is of great significance in the key aspects of treating chronic wounds, including reducing oxidative stress, promoting angiogenesis, and improving the natural remodeling of extracellular matrix and immune regulation. In this study, we prepared a composite hydrogel, sodium alginate (SA)@MnO2/recombinant humanized collagen III (RHC)/mesenchymal stem cells (MSCs), composed of SA, MnO2 nanoparticles, RHC, and MSCs. The hydrogel has high mechanical properties and good biocompatibility. In vitro, SA@MnO2/RHC/MSCs hydrogel effectively enhanced the formation of intricate tubular structures and angiogenesis and showed synergistic effects on cell proliferation and migration. In vivo, the SA@MnO2/RHC/MSCs hydrogel enhanced diabetes wound healing, rapid re-epithelization, favorable collagen deposition, and abundant wound angiogenesis. These findings demonstrated that the combined effects of SA, MnO2, RHC, and MSCs synergistically accelerate healing, resulting in a reduced healing time. These observed healing effects demonstrated the potential of this multifunctional hydrogel to transform chronic wound care and improve patient outcomes.

Development and application of modified biocarrier immobilized with Bacillus sp. for azo dye degradation: batch and continuous study

The rapid growth of the industry and urbanization induces the consumption of large amounts of freshwater. In the meantime, untreated or partial treatment of industrial (especially textile) wastewater creates a threat to the living system. Azo dyes are generally used in textile industries and cause hazardous effects due to their recalcitrant and toxic nature. The present work emphasized the synergetic effect of adsorption and biodegradation of a modified biocarrier on Congo red (CR) dye removal. The modified biocarrier was developed by entrapping the polyurethane foam and activated carbon with sodium alginate. The adsorption effect was better explained by the Langmuir isotherm than Freundlich isotherm. Various independent factors, including pH, dissolved oxygen (DO), and dye concentration, were optimized in a fixed bed bioreactor (FBBR) filled with Bacillus sp. immobilized modified biocarrier. The highest removal of 95.43% was evaluated at a pH of 7.0, DO of 5.0 mg O2/L, and inlet CR dye concentration of 100 mg/L. Moreover, the continuous operation of FBBR achieved a 91.13% dye removal at an inlet loading rate of 216 mg/L. d at an initial dye concentration of 300 mg/L. The present approach could be an efficient technology for azo dye treatment.

In situ chemoimmunotherapy hydrogel elicits immunogenic cell death and evokes efficient antitumor immune response

BackgroundChemoimmunotherapy has shown promising advantages of eliciting immunogenic cell death and activating anti-tumor immune responses. However, the systemic toxicity of chemotherapy and tumor immunosuppressive microenvironment limit the clinical application.MethodsHere, an injectable sodium alginate hydrogel (ALG) loaded with nanoparticle albumin-bound-paclitaxel (Nab-PTX) and an immunostimulating agent R837 was developed for local administration. Two murine hepatocellular carcinoma and breast cancer models were established. The tumor-bearing mice received the peritumoral injection of R837/Nab-PTX/ALG once a week for two weeks. The antitumor efficacy, the immune response, and the tumor microenvironment were investigated.ResultsThis chemoimmunotherapy hydrogel with sustained-release character was proven to have significant effects on killing tumor cells and inhibiting tumor growth. Peritumoral injection of our hydrogel caused little harm to normal organs and triggered a potent antitumor immune response against both hepatocellular carcinoma and breast cancer. In the tumor microenvironment, enhanced immunogenic cell death induced by the combination of Nab-PTX and R837 resulted in 3.30-fold infiltration of effector memory T cells and upregulation of 20 biological processes related to immune responses.ConclusionsOur strategy provides a novel insight into the combination of chemotherapy and immunotherapy and has the potential for clinical translation.

Precisely Printable Silk Fibroin/Carboxymethyl Cellulose/Alginate Bioink for 3D Printing.

Three-dimensional (3D) bioprinting opens up many possibilities for tissue engineering, thanks to its ability to create a three-dimensional environment for cells like an extracellular matrix. However, the use of natural polymers such as silk fibroin in 3D bioprinting faces obstacles such as having a limited printability due to the low viscosity of such solutions. This study addresses these gaps by developing highly viscous, stable, and biocompatible silk fibroin-based inks. The addition of 2% carboxymethyl cellulose sodium and 1% sodium alginate to an aqueous solution containing 2.5 to 5% silk fibroin significantly improves the printability, stability, and mechanical properties of the printed scaffolds. It has been demonstrated that the more silk fibroin there is in bioinks, the higher their printability. To stabilize silk fibroin scaffolds in an aqueous environment, the printed structures must be treated with methanol or ethanol, ensuring the transition from the silk fibroin's amorphous phase to beta sheets. The developed bioinks that are based on silk fibroin, alginate, and carboxymethyl cellulose demonstrate an ease of printing and a high printing quality, and have a sufficiently good biocompatibility with respect to mesenchymal stromal cells. The printed scaffolds have satisfactory mechanical characteristics. The resulting 3D-printing bioink composition can be used to create tissue-like structures.

Formulation and evaluation of hydrocortisone micro beads

The current study aimed to develop hydrocortisone mucoadhesive microbeads to prolong the drug's action in the gastrointestinal system, targeting Crohn's disease treatment. Hydrocortisone, known for its anti-inflammatory and anti-rheumatic effects, was utilized in bead form to enhance therapeutic efficacy, extend residence time, and reduce dosage frequency. Using sodium alginate, HPMC, and Eudragit L-100 as adhesive polymers, and calcium chloride and aluminium chloride as cross-linking agents, the study crafted microbeads with an entrapment efficiency between 57.23% and 91.69%. Evaluations focused on in vitro drug release, particle size, surface characteristics, entrapment efficiency, and the role of cross-linking ions. Of the formulations, HCS-8 (with sodium alginate and Eudragit L-100 using aluminium chloride as the gelling solution) and HCS-2 showed optimal drug release profiles. Notably, HCS-8 achieved a 12-hour drug release delay, attributed to aluminium chloride's cross-linking action. Drug release kinetics revealed a zero-order linearity (R2=0.99), suggesting super case 2 transport as the primary release mechanism.

Synthesis and characterization of an innovative sodium alginate/polyvinyl alcohol bioartificial hydrogel for forward-osmosis desalination.

Recently, hydrogels have been widely applied as draw agents in forward osmosis (FO) desalination. This work aims to synthesize bioartificial hydrogel from a blend of sodium alginate (SA) and polyvinyl alcohol (PVA) using epichlorohydrin (ECH) as a crosslinker. Then this prepared hydrogel was applied as a draw agent with cellulose triacetate membrane in a batch (FO) cell. The effects of the PVA content in the polymer blend and the crosslinker dose on the hydrogel's swelling capacity were investigated to optimize the hydrogel's composition. Furthermore, the water flux and the reverse solute flux of the optimum SA/PVA hydrogel were evaluated in a batch (FO) unit under the effect of the hydrogel's particle size, feed solution (FS) temperature, FS concentration, and membrane orientation. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and compression strength tests were used to characterize the prepared hydrogel. Results revealed that the equilibrium swelling ratio (%) of 5228 was achieved with a hydrogel that had 25% PVA and a crosslinking ratio of 0.8. FO experiments revealed that the maximum water flux of 0.845 LMH achieved, when distilled water was used as FS, average hydrogel's particle size was 60µm, and the FS temperature was 40°C.

L-Cysteine Cross-Linked Sodium Alginate as a Binder with Strong Binding Force on Copper Foils To Enhance Sodium Storage Performance

<i>L</i>-Cysteine Cross-Linked Sodium Alginate as a Binder with Strong Binding Force on Copper Foils To Enhance Sodium Storage Performance

DEVELOPMENT AND OPTIMIZATION OF RAFT-FORMING FORMULATION OF H2BLOCKERS

Objective: The present research work is focused to develop in situ raft gel of Nizatidine. sodium alginate (SA) is one of the critical components for the development in situ raft system. Methods: The formulation was prepared using polymers such as SA and gellan gum. The formulations were subjected to evaluation characteristics such as pH, in vitro gelling capacity, viscosity, gel strength, and in vitro release studies. Results: The pH of all the prepared batches was found in the range of 6.4–7.2 for S1–S9, and 6.3–7.2 for G1–G9. S1–S9 formulations showed viscosity in the range of 253.7–400.9 cps, and G1–G9 formulations showed viscosity in the range of 253.4–399.8 cps. Formulation S6 containing SA and G6 containing gellan gum gave the highest drug content of 99.58% and 99.5%, respectively. The highest gel strength 4.6 is exhibited by S6 and G6 formulations. Formulation S6 containing SA gave the highest drug release of 95.62% and also showed sustained and controlled release for up to 12 h. Conclusion: Gastric raft formulation is a better choice for drugs such as Nizatidine which enhances the drug release for a prolonged time by remaining buoyant in the stomach for more than 12 h.

Comparative study on the different edible coatings loaded with fennel essential oil/β-cyclodextrin microcapsules for blueberry preservation

ABSTRACT Fennel essential oil was encapsulated in β-cyclodextrin to prepare microcapsules (β-CD-FEO). Single-factor experiments and model fitting were used to optimise the microcapsules. When the optimal core/wall material ratio was 10:0.6, encapsulation time set as 90 min, and encapsulation temperature controlled at 60°C, an optimal encapsulation efficiency of 77.05 ± 0.14% can be obtained. Using β-CD-FEO blended with low acyl gellan gum (LA-GG) as main constituents, three-component coating solutions containing sodium alginate (SA), sodium carboxymethyl cellulose (CMC-Na), and konjac glucomannan (KGM) were investigated to evaluate their effect on the preservation of blueberries. Compared with the noncoated sample, coated blueberries showed excellent storage properties, especially KGM/LA-GG/β-CDs-FEO group had the highest sensory evaluation score under 25°C for 8 days. Therefore, KGM/LA-GG/β-CDs-FEO has potential application value in maintaining the quality of blueberries.

Oxidized sodium alginate hydrogel-mouse nerve growth factor sustained release system promotes repair of peripheral nerve injury

In recent years, mouse nerve growth factor (mNGF) has emerged as an important biological regulator to repair peripheral nerve injury, but its systemic application is restricted by low efficiency and large dosage requirement. These limitations prompted us to search for biomaterials that can be locally loaded. Oxidized sodium alginate hydrogel (OSA) exhibits good biocompatibility and physicochemical properties, and can be loaded with drugs to construct a sustained-release system that can act locally on nerve injury. Here, we constructed a sustained-release system of OSA-mouse nerve growth factor (mNGF), and investigated the loading and release of the drug through Fourier transform infrared spectroscopy and drug release curves. In vitro and in vivo experiments showed that OSA-mNGF significantly promoted the biological activities of RSC-96 cells and facilitated the recovery from sciatic nerve crush injury in rats. This observation may be attributed to the additive effect of OSA on promoting Schwann cell biological activities or its synergistic effect of cross-activating phosphoinositide 3-kinase (PI3K) through extracellular signal regulated kinase (ERK) signaling. Although the specific mechanism of OSA action needs to be explored in the future, the current results provide a valuable preliminary research basis for the clinical application of the OSA-mNGF sustained-release system for nerve repair.

Biocompatible sodium alginate–silk fibroin antibacterial microspheres from a microfluidic platform for infected wound repair

Micro/nano drug delivery systems can provide ideal controlled drug release. Microfluidic chip technology plays an important role in the preparation of microspheres. Sodium alginate (SA) has been used to prepare microspheres as drug carriers owing to its good biosafety and easy preparation. However, these microspheres lack antimicrobial activity and drug loading efficiency, which prevent their application for infected wound repair. Although silver nanoparticles (AgNPs) possess broad-spectrum antibiotic activity, liquid mixtures of AgNPs and SA are too unstable to fabricate drug-loaded microspheres using microfluidic chip technology. In this study, AgNPs were coated with silk fibroin (SF) and then dispersed in SA solution to fabricate antibacterial microspheres (denoted SA-SF-Ag) using microfluidic chip technology. SA-SF-Ag effectively inhibited the growth of microorganisms and gradually released AgNPs. Moreover, in vivo results showed that SA-SF-Ag promoted infected wound healing and angiogenesis by killing Pseudomonas aeruginosa on the surface of infected skin wounds of mouse models. This study offers a new method to integrate AgNPs into organic polymeric microspheres for the treatment of infected wounds.

ZnO and Fe2TiO5 nanoparticles obtained by green synthesis as active components of alginate food packaging films

The aim of this study was to develop an active alginate packaging film incorporating antioxidant Fe2TiO5 and antibacterial ZnO nanoparticles, obtained by green synthesis utilizing citrus peel waste. The average particle size was estimated as 10 nm for ZnO and 50 nm for Fe2TiO5. Films were prepared using 2.33% (w/v) sodium alginate with 0.11% (w/v) Fe2TiO5 and/or ZnO nanoparticles. The inclusion of nanoparticles resulted in a noticeable colour difference, reduced the transparency, increased UV light protection and improved thermal stability of the film. The dry matter content of the films was around 83%. Film solubility in distilled water was low (< 8%) mainly reflecting crosslinking of the alginate polymer and Ca2+-ions. The lowest swelling degree was obtained for the ZnO/Fe2TiO5 –alginate film (178%). The efficiency of these packaging films was demonstrated through preservation of strawberry freshness. Alginate packaging film with a mixture of metal oxide nanoparticles can facilitate food safety and increase food shelf life.

An "All-In-One" Immunomodulator-Engineered Clinical Translatable Immunotherapy of Advanced Hepatocellular Carcinoma.

Clinical treatment of advanced hepatocellular carcinoma (HCC) remains a significant challenge. Utilizing1-bromoacetyl-3,3-dinitroazetidine (RRx-001) to downregulate the expression of innate immune checkpoint molecule, cluster of differentiation 47 (CD47), provides a powerful means for treating advanced HCC containing abundant immunosuppressive macrophages. Herein engineering of a previously optimized Doxorubicin (DOX)-delivery nanoplatform based on sodium alginate is reported to further co-deliver RRx-001 (biotinylated aldehyde alginate-doxorubicin micelle prodrug nanoplatform, BEA-D@R) for efficient immunotherapy of advanced HCC. Thisgroundbreaking technique reveals the "all-in-one" immunotherapeutic functionalities of RRx-001. Besides the previously demonstrated functions of downregulating CD47 expression and increasing reactive nitrogen species (RNS) generation, another key function of RRx-001 for downregulating the expression of the adaptive immune checkpoint molecule programmed cell death 1 ligand 1 (PDL1) is first uncovered here. Combined with the reactive oxygen species (ROS) generation and an upregulated "eat me" signal level of DOX, BEA-D@R collectively increases RNS generation, enhances T-cell infiltration, and maximizes macrophage phagocytosis, leading to an average of 40% tumor elimination in a mice model bearing an initial tumor volume of ≈300 mm3 that mimics advanced HCC. Overall, the "all-in-one" immunotherapeutic functionalities of a clinical translatable nanoplatform are uncovered for enhanced immunotherapy of advanced HCC.

Measuring cell proliferation in bioprinting research

Tissue-like constructs, intended for application in tissue engineering and regenerative medicine, can be produced by three-dimensional (3D) bioprinting of cells in hydrogels. It is essential that the viability and proliferation of the encapsulated cells can be reliably determined. Methods currently used to evaluate cell proliferation, such as quantification of DNA and measurement of metabolic activity, have been developed for application in 2D cultures and might not be suitable for bioinks. In this study, human fibroblasts were either cast or printed in gelatin methacryloyl (GelMA) or sodium alginate hydrogels and cell proliferation was assessed by AlamarBlue, PicoGreen and visual cell counts. Comparison of data extrapolated from standard curves generated from 2D cultures and 3D hydrogels showed potential inaccuracies. Moreover, there were pronounced discrepancies in cell numbers obtained from these assays; the different bioinks strongly influenced the outcomes. Overall, the results indicate that more than one method should be applied for better assessment of cell proliferation in bioinks.